g4 PRACTICAL ORGANIC CHEMISTRY
dracetic acid CSH8O4. . It is converted into the sodium salt t>y
boiling with soda solution with the addition of animal ch&r-
coal. & The sodium salt crystallises from the nitrate. O&
adding dilute sulphuric acid, the free acid is obtained as colour-
less needles ; m. p. 109°.
i. 2C,H5OH + Na2 = 2NaOC2H5 + H2
2 CILCO.OC.,H5 + NaOC«HB= CII3
CO.OCoHfl + C
The formation of ethyl acetoacetate occurs, according- to
Claisen, in four steps. The presence of a small quantity of
alcohol gives rise to sodium ethylate, which forms an additive
compound with ethyl acetate. The latter unites with a second
molecule of ethyl acetate yielding the sodium salt of ethyl aceto-
acetate, and splitting off alcohol, which reacts with fresh metallic
sodium. The sodium salt on acidifying passes into the tauto-
meric (ketonic) form of acetoacetic ester.
Properties.—Colourless liquid possessing a fruity smell ; b. p.
181°; sp. gr. 1*03 at 15°. Boiled with dilute caustic potasli,
the ester decomposes into alcohol, carbon dioxide, and acetone
(ketonic decomposition), with strong or alcoholic caustic potasli,
sodium acetate and alcohol are formed (acid decomposition).
Reactions.—i. Add a drop of ferric chloride dissolved in alcohol
to a few drops of the ester ; a deep violet coloration is produced.,
2. Add i c.c. of a saturated alcoholic solution of cupric acetate
to a few drops of the ester, a bluish-green crystalline precipitate
of copper acetoacetic ester, (CcH9O3)2Cuj is formed See
Appendix, p. 248. " jv";
Distillation in vacuo.—The apparatus is shown infcig-. 56.
The distilling flask is provided with a thermometer and attach eel
to a short condenser and receiver. The receiver consists of a.